Fibers of acrylonitrile-alkyl alphaacylamino acrylate copolymer



United States PatentO FIBERS OF ACRYLONITRILE-ALKYL ALPHA- ACYLAMINO ACRYLATE COPOLYMER Joseph B. Dickey, Rochester, N. Y., Harry W. Coover, Klngsport, Tenn., and Theodore E. Stanin, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application August 17, 1950, Serial No. 180,104

3 Claims. (Cl. 260-855) This invention relates to spinning copolymers derived from acrylonitrile and alkyl esters of a-acetamino acrylic acid in order to form filaments or like shaped articles therefrom. More particularly, this invention concerns an improved process for spinning such acrylonitrile copolymers whereby shaped articles such as filaments, fibers and the like are produced substantially free of voids, having an attractive lustrous appearance, a high tenacity, an improved light and gas rastness, an improved dyeability and moisture aflinity and, in addition, having the important characteristic of a relatively high temperature softening point.

The production of yarn from unmodified polyacrylonitrile has been achieved heretofore and such yarn has a high tenacity with a desirable high softening point of about 220 C. These properties, particularly the high softening point, which is lacking in other vinyl polymer fibers, is a necessary characteristic if the fiber is to be employed in textile materials. Such unmodified polyacrylonitrile yarns, however, lack other properties which are necessary in a generally useful textile material suitable for clothing manufacture. These properties, which are not found in unmodified polyacrylonitrile yarns or textiles, are good dyeability and aifinity for moisture. Without these additional properties the usefulness of the yarn is limited for many purposes.

The dye afiinity and moisture absorption of polyacrylonitrile type yarn has been improved by copolymerizing acrylonitrile with compounds containing hydrophylic groups; e. g., carboxyl, ester, amido, amino and hydroxyl groups. This may readily be accomplished by employing as the other polymer such compounds such as vinyl acetate, acrylamide and acrylic acid. Desirable improvements as respects dyeability and moisture absorption are secured by polymerizing with about 15-40% of these modifiers but at the expense of the softening point of the fiber. The inclusion of such modifiers invariably results in a lowering of the softening point of from 40- 100 C. depending on the nature and amount of modifier present. Such modified polyacrylonitrile fibers shrink greatly in hot water and fuse under a flat-iron at normal ironing temperatures which are employed for pressing textile fabrics. Consequently, the polyacrylonitrile fibers thus modified are still of limited application in the textile industry.

An object, therefore, of the present invention is an improved process for forming copolymers of acrylonitrile and alkyl esters of a-acylamino acrylic acid into shaped articles.

Another object of the invention is to provide new and improved filaments and yarns from copolymers of acrylonitrile and alkyl esters of a-acyl amino acrylic acid characterized by freedom from voids, a lustrous appearance, a high tenacity and extensibility, an improved dyeability, an improved light and gas fastness, and a relatively high sticking temperature.

Still another object is to provide a process for Wet spinning copolymers of acrylonitrile and an alkyl a-acylamino acrylate into filaments in an aqueous coagulating bath.

Yet another object is a process of spinning such acrylonitrile modified polymers which includes stretching the filaments to improve their structure.

"ice

Other objects will be apparent from the following detailed description of the invention.

in accordance with the invention, We have found that solutions of copolymers of acrylonitrile and alkyl esters of a-acylamino acrylic acid containing 15 to 40% of the ester by weight may be forced through a suitable spinnerette and coagulated in an aqueous bath to form a filament which preferably is then passed through an atmosphere of hot air maintained approximately from 60 C. to C. The filament is preferably stretched while passing through the hot air atmosphere in accordance with the amount of draft desired. Stretching improves the continuity of the filament and reduces voids therein. Bundles of such filaments may be twisted into thread by any desirable method. Yarns which contain acrylonitrile copolymerized with 20-35% of the ester especially have excellent afinity for acetate, basic, acid and insoluble vat dyes and good affinity for direct and soluble vat dyes. Of special importance is their relatively high sticking temperatures, fastness to light and gas fumes, and desirable moisture aflinity. We have found that certain blue dyes which are not fast to gas fumes when on acetate yarn are substantailly unaffected when the fibers of the instant invention are dyed with them. Any suitable spinning apparatus known in the prior art and equipped with means for forcing the spinning solution through a spinnerette into a coagulating bath may be employed. The associated drying chamber may be conventional and the stretching may be carried out by a system of drums running at increasing rates as is common in this art.

The alkyl a-acylaminoacrylates which may be employed in our invention to copolymerize with acrylonitrile may be represented by the following general formula:

wherein R represents an alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, etc., groups (e. g., an alkyl group containing from 1 to 4 carbon atoms), and R1 represents an alkyl group such as methyl, ethyl, n-propyl, isopropyl, etc., groups (e. g., an alkyl group containing from 1 to 3 atoms).

Representative esters, in accordance with the above general formula, for example, include: Methyl a-acetaminoacrylate, ethyl a-acetaminoacrylate, n-propyl a-acetaminoacrylate, isopropyl a. -acetaminoacrylate, n-butyl a-acetaminoacrylate, methyl a-propionaminoacrylate, ethyl a-propionaminoacrylate, n-butyl a-propionaminoacrylate, methyl a-n-butyraminoacrylate, ethyl a-n-butyraminoacrylate, isobutyl a-n-butyraminoacrylate, methyl a-isobutyraminoacrylate, ethyl a-isobutyraminoacrylate, n-propyl a-isobutyraminoacrylate, iso-butyl a-isobutyraminoacrylate.

The alkyl a-acylamirloacrylates represented by the above general formula can be prepared according to the general method described in the copending application, Serial No. 87,356 filed April 13, 1949, of H. W. Coover, Jr., and Joseph B. Dickey, now Patent No. 2,548,518. The process described in that application comprises reacting an alkali metal salt of an ct-acylaminoacrylic acid with a dialkyl sulfate. The alkali metals useful for this purpose comprise those set forth in Serial No. 87,356 and also those alkali metal salts of the wacylaminoacrylic acids described in the copending application, Serial No. 132,216, filed December 9, 1949, of H. W. Coover, Jr., and Joseph B. Dickey, now Patent No. 2,622,074. Suitable methods for preparing copolymers of acrylonitrile and alkyl a-acylaminoacrylates are describedin the patent literature and methods particularly acrylonitrile and alkyl a-acylamino acrylate may be dissolved in various solvents for example dimethyl formamide, dimethylacetamide, ethylene carbonate, ethylene carbamate, N methyl 2 pyrrolidone, 'y-butyrolactone, succinonitrile, y-valerolactone, and tetramethylene cyclic sulfone.

The invention is further illustrated in the following examples:

Example 1.Two parts of ethyl a-acetamino acrylate and 8 parts of acrylonitrile are added to 100 parts of distilled water to which 0.1 part of ammonia persulfate and 0.2 part of sodium bisulfate are added. The reaction vessel is sealed from the outside air and maintained at 35-40 C. for 18 hours. A fine white insoluble poly- 4 Table II The effect of the composition of the coploymer on the sticking point of the fibers as measured on a Dennis bar is illustrated in the following table:

Stlckln Sticking P mt o Percent Methyl ester Point o O Percent Ethyl ester mer is formed which is filtered off and thoroughly washed with water, then dried. 9.1 parts of a copolymer of The general etteet 0f mcreasmg the amount of alkyl acrylonitrile and ethyl u-acetamino acrylate are obtained 'acylflmmo.acrylate above 40% Is to further 9 the which softens at 200 C. on a Dennis bar and which ,softemhg P t of e copolymer h Very slghlficaht contains 23.3% of ethyl a-acetamino acrylate as calculmprovemeht 1h dyelhg Propemes 1S h e lated from carbon analysis. This copolyrner is readily 1f the P e t of the allryl ot'eeylamlho acrylate 1h soluble in dimethyl formamide and dimethyl acetamide. the aqrylomtrlle p y q 1S reduced below 15% other The inherent viscosity is 2.1 measured as a 0.25% soluhhdeslrehle features are lhtrodheed- For example, t tionin dimethyl f id composition of copolymer of 5 methyl ot-acetamlno Example 2.-Three parts methyl a-acetamino acrylate acrylate and 95% acrylonltrlle disclosed in U. S. Ifatent and 7 parts acrylonitrile are added to 100 parts of 2,461,383 of February 8,1949 15 h y sllghtly distilled water to which 0.1 part of ammonia persulfate better as sp y ty and moisture ahsorptwn and 0.2 part of sodium bisulfate are added. The reh hrlmodlhed polyaeryllohltrlle and q e y 15 h action vessel is Sealed f the id hahd i satisfactory as a compositlon to make into textlle fabrics. tained at 35-40" c. for 18 hours. A fine white inh Practical range of composition of these copolymers soluble polymer is formed which is filtered off and h between and 40% and the most deslrahle P p thoroughly washed with water, then dried. 7.5 parts hes are Ohtalhed t of copolymer of acrylonitrile and methyl a-acetarnino The Polyaerylomtrlle hsefhl 1h Praetlelhg our y acrylate containing 27.2% of methyl a-acetamino tlon can be prepared according to the process described acrylate are obtained which had softening point of In Patent 2,434,054 of January 1948, Or 220 C. as measured by a Dennis bar. The inherent 35 Patent 2,296,403 of September 1942; other F viscosity is 1.9 as measured in a 0.25% solution in diw s Whwh can mp y q p p ap y yl methyl f id nltrlle are descrlbed 1n copendlng appllcatlons, Serlal Example 3.--A spinning procedure by which these co- 49,653, l filed September polymers may be spun into filaments, in accordance with 1948, 111 the r1ame of Stamh, COOVer, another feature of the invention, is now described. 40 h yi the first two of Whleh Issued p A spinning solution of the copolymer prepared in y Patent 2,629,711 and 2,629,712 and the Example 2 was made up by dissolving 6.4 grams of thlrd h ahfahdehedpolymer in 40 cc. of dimethyl formamide. This dope AS mdlfla'ted 111 the feregolhg examples, eoagulatlhg was filtered by pressure into a spinning chamber con- P Of dlstllletl Water y be advantageously p y taining a 0.1 mm. single hole spinnerette. The dope was 111 Our Wet p l P However, 1f desll'ed e a h extruded into a water bath by applying 40 p. s. i. presy also contain e of the P B to sure from a nitrogen tank. The coagulated monofilathe P h p y In Preparlhg the splhhmg ment was taken up on a roll rotating at a peripheral that 15 being p W have found that t precipitating rate of 18 ft./min., then drawn through a hot-air chamhath y he eomprred of Water Varymg from 25 to 1361'. at 140 C. and wound on a drum traveling at a 100%, the balance being a solvent of the type contained peripheral rate of 72 ft./min. This stretching rate is m t pe or another Olvent q the t p y regulated according to the amount of draft desired. and Whlle there 18 110 heed 0f lheorporatlng Sp Salts of can be increased up to 126 ft./min. The thread guide alcohols mto the bath whe1 1 qp 1n ance through which the filament passes just before being Wlth e Present lhvehtlorli 1t 15 pp that the wound on h d i h d to a mechanism hi h corporation of smallarnounts of some of these salts and can shift its position every fifty revolutions of the drum Chemicals are hot lhlhrlohsso that individual bundles of fifty monofilaments can The filaments s d gnera1ly rema1n the aqueous be collected from the drum and twisted into a thread bath for a SUffiCIeHt time and dlstance to substantially which can be tested on conventional textile yarn testing or nearly Completely eoaghlate the filamehts- The machinery. The yarn samples were tested before and sequent high temperature drying step is an important after shrinkage in boiling water. feature of this process. The temperature of the air for The fibers containing 20-35% of the ester had exy h P p must he at least ahd y he cellent affinity for acetate, basic, acid and insoluble vat as g as C: Preferably to C- It dyes and good afiinity for direct and soluble vat dyes. is also desirable that the filament contain an appreciable Example 4.fi9imilar acrylonitrile coploymers were quantity of solvent when it enters the drying chamber, prepared containing 15 to 40% of an alkyl u-acylaminousually 5 to 25% of the solvent associated with the polyacrylate and spun in accordance with the methods demer in the spinning solution. The high temperature scribed above and other desirable properties of fibers of the drying permits rapid removal of the water and made in accordance with the present invention are shown a most of the residual solvent and at the same time the in the following tables. presence of the solvent permits the polymer to flow Table 1 Unshr Sh oymer otupos 1011 W BCOV- 35 9 gggg th Ten. Ext. 2%?

Percent Percent Percent Percent Percent 22% methyl ester 2. 56 7 1l 2. 0 16 70 4.1 27% methyl esten. 1.46 12 17 1.45 20 67 32% methyl ester 1 48 12 19 1.57 23 68 4.8 40% methyl este 1 63 8 16 1.27 19 69 23% ethyl ester. 1 40 13 12 1.46 20 69 3.6 33% ethylester 1 6 10 13 1.74 20 70 5.9

slightly, thus removing voids in the yarns produced in the spinning bath. Under proper conditions, the yarn emerges from the drying operation without any appreciable number of voids, and is dry enough to permit stretching to produce greater strength. The heating step is preferably employed, since these freshly spun yarns, if dried at temperatures appreciably less than 60 C. say from 25 C. to 50 C., can be stretched only with dilficulty and will contain numerous voids and be generally unsuited for use in the textile art.

We claim:

1. A synthetic fiber characterized by a high density and extensibility and a sticking temperature of above 185 C., comprising a copolymer of 65 to 80% by Weight of acrylonitrile and 20 to 35% by weight of an alkyl a-acylamino acrylate wherein the acyl group is the un substituted acyl group of a saturated aliphatic monocarboxylic acid containing 2 to 4 carbon atoms and the alkyl group contains 1 to 4 carbon atoms.

2. A synthetic fiber characterized by a high density and extensibility and a sticking temperature of 185 C. to 210 C., comprising a copolymer of 65 to 80% by weight of acrylonitrile and to by weight of methyl a-acetarninoacrylate.

3. A synthetic fiber characterized by a high density and extensibility and a sticking temperature of 185 C. to 210 C. comprising a copolymer of to by weight of acrylonitrile and 20 to 35% by weight of ethyl a-acetaminoacrylate.

References Cited in the file of this patent UNITED STATES PATENTS 2,404,722 Houtz July 23, 1946 2,461,383 Isaacs et a1. Feb. 8, 1949 2,527,863 Webb Oct. 31, 1950 2,570,200 Bruson Oct. 9, 1951 

1. A SYNTHETIC FIBER CHARACTERIZED BY A HIGH DENSITY AND EXTENSIBILITY AND A STICKING TEMPERATURE OF ABOVE 185* C., COMPRISING A COPOLYMER OF 65 TO 80% BY WEIGHT OF ACRYLONITRILE AND 20 TO 35% BY WEIGHT OF AN ALKYL A-ACYLAMINO ACRYLATE WHEREIN THE ACYL GROUP IS THE UNSUBSTITUTED ACYL GROUP OF A SATURATED ALIPHATIC MONOCARBOXYLIC ACID CONTAINING 2 TO 4 CARBON ATOMS AND THE ALKYL GROUP CONTAINS 1 TO 4 CARBON ATOMS. 